It is known that when molecules or atoms (ions) are confined in an isolated three-dimensional space formed by other molecules, the molecules or atoms (ions) show a specific behavior. Attempts have been made to improve reactivity, membrane permeability, and the like by utilizing such a phenomenon.
The present inventors established a method that efficiently produces a hollow metal complex that includes an isolated three-dimensional space in the molecule, and have developed technology that utilizes the hollow metal complex (see Non-patent Document 1 and Patent Documents 1 to 5, for example).
Non-patent Document 2 discloses that a polysaccharide functions as a catalyst for a polycondensation reaction (sol-gel polymerization) of a silicon alkoxide such as tetra(2-hydroxyethoxy)silane (THEOS). Non-patent Document 3 discloses that a lotus-shaped silica structure is obtained by a sol-gel reaction of tetraethoxysilane (TEOS) using a sugar compound as a template.